1. Field of the Invention
The present invention relates to an intaglio printing press, and especially, one useful when applied to printing of banknotes or securities.
2. Description of the Related Art
FIG. 4 shows an example of a conventional intaglio printing press applied to printing of banknotes or securities (see, for example, Japanese Examined Patent Publication No. 2-42070). As shown in FIG. 4, a plate cylinder 112 having an intaglio plate mounted on an outer peripheral surface thereof is contacted with an impression cylinder 111. To the plate cylinder 112, an ink collecting cylinder 113 having rubber blankets mounted on an outer peripheral surface thereof is opposed in contact with the plate cylinder 112. To the ink collecting cylinder 113, three chablon rollers 114 are opposed in contact with the ink collecting cylinder 113 along a circumferential direction of the ink collecting cylinder 113. To each of these chablon rollers 114, an ink fountain or reservoir 117 filled with ordinary ink for printing of a main pattern is opposed in contact with the chablon roller via an ink fountain roller 116 and intermediate rollers 115. To the plate cylinder 112, a chablon roller 118 is also opposed in contact therewith. To this chablon roller 118, an ink fountain 121 filled with special ink, such as OVI (Optical Variable Ink), for printing of a pattern for forgery prevention is opposed in contact with the chablon roller 118 via an ink fountain roller 120 and intermediate rollers 119. Opposite the plate cylinder 112 and downstream from the ink collecting cylinder 113, a wiping roller 122 is disposed, in contact with the plate cylinder 112, for removing surplus ink adhering to the surface of the intaglio plate. The wiping roller 122 is immersed in a solvent stored in a wiping tank 123.
The foregoing conventional intaglio printing press is operated in the following manner:
When each ordinary ink is supplied from inside the ink fountain 117 to the chablon roller 114 via the ink fountain roller 116 and the intermediate rollers 115, each such ink is fed to the ink collecting cylinder 113, and then to the intaglio plate of the plate cylinder 112. On the other hand, when special ink is supplied from inside the ink fountain 121 to the chablon roller 118 via the ink fountain roller 120 and the intermediate rollers 119, the special ink is directly fed to the intaglio plate of the plate cylinder 112. The inks supplied to the intaglio plate of the plate cylinder 112 have their surplus amounts removed by the wiping roller 118. The remaining inks on the intaglio plate of the plate cylinder 112 are transferred to a sheet passed on to the impression cylinder 111 to perform printing.
Special ink, such as the aforementioned OVI, is expensive and has poor transfer characteristics. Thus, when it is supplied from the ink fountain 121 to the intaglio plate of the plate cylinder 112 via the ink fountain roller 120, the intermediate rollers 119, and the chablon roller 118, its loss increases, thereby deteriorating printing quality, and making the printing cost very high. Methods for minimizing the use of the intermediate rollers 119, etc. have been worked out, but have been unsuccessful in obtaining satisfactory results.